AT89C51RD2 Atmel Corporation, AT89C51RD2 Datasheet - Page 72

• Manufacturer Part Number: AT89C51RD2
• Manufacturer: Atmel Corporation

Specifications of AT89C51RD2

• Flash (kbytes): 64 Kbytes
• Max. Operating Frequency: 60 MHz
• Cpu: 8051-12C
• Max I/o Pins: 32
• Spi: 1
• Uart: 1
• Sram (kbytes): 2
• Self Program Memory: API
• Operating Voltage (vcc): 2.7 to 5.5
• Timers: 4
• Isp: UART
• Watchdog: Yes

17. Interrupt System
Figure 17-1. Interrupt Control System
72
AT89C51RD2/ED2
EXF2
KBD IT
SPI IT
INT0
INT1
PCA IT
TF0
TF1
TF2
RI
TI
The AT89C51RD2/ED2 has a total of 9 interrupt vectors: two external interrupts (INT0 and
INT1), three timer interrupts (timers 0, 1 and 2), the serial port interrupt, SPI interrupt, Keyboard
interrupt and the PCA global interrupt. These interrupts are shown in Figure 17-1.
Each of the interrupt sources can be individually enabled or disabled by setting or clearing a bit
in the Interrupt Enable register
disable bit, which must be cleared to disable all interrupts at once.
Each interrupt source can also be individually programmed to one out of four priority levels by
setting or clearing a bit in the Interrupt Priority register
High register
with each combination.
Individual Enable
(Table 17-5
IE0
IE1
and
IPH, IPL
Table
(Table 17-4
17-6) shows the bit values and priority levels associated
Global Disable
3
0
3
0
3
0
3
0
3
0
3
0
3
0
3
0
3
0
and
Table
17-6). This register also contains a global
(Table
17-7) and in the Interrupt Priority
High Priority
Interrupt
Interrupt
Polling
Sequence, Decreasing from
High to Low Priority
Low Priority
Interrupt
4235K–8051–05/08